Pre-chemo nod for Medivation's Xtandi sets up showdown with J&J's Zytiga

Johnson & Johnson's ($JNJ) next-gen prostate cancer pill, Zytiga, has been cruising since it hit the market back in April 2011, but now, it may be vulnerable to market share losses for the first time. The FDA has approved Medivation and Astellas' rival, Xtandi, for use in prostate cancer patients before chemo, giving the pill a head-to-head shot at J&J's blockbuster.

U.S. regulators based the new nod on Phase III trial data that showed that Xtandi posted an overall survival benefit, cutting the risk of death by 29% compared with placebo. It also reduced the risk of disease progression and delayed both skeletal problems and the need for chemo, the company said Wednesday.

Thanks to those results--and the subsequent label expansion--Medivation should now see its patient pool widen significantly, Sanford Bernstein analyst Geoffrey Porges told Reuters. "The average duration of treatment should double and the addressable patient population triple in the pre-chemo setting," he said.

And, for the first time since its rollout--nearly a year and a half after J&J's--it'll also be able to set its sights on a face-off with Zytiga. The J&J pill already boasts a pre-chemo indication, which helped it churn out $1.07 billion in first-half 2014 sales.

Xtandi, which netted $143.7 million in second-quarter U.S. sales, has the convenience factor on its side, as it's used solo; patients take Zytiga alongside prednisone. And according to Leerink Partners analyst Howard Liang, the solid uptake the drug has seen in post-chemo patients bodes well for its head-to-head chances, too.

"Strong adoption of Xtandi among oncologists as the preferred agent in the post-chemo setting, in our opinion, speaks to the preference for Xtandi's advantage that goes beyond lack of steroid co-administration and sets up potentially an even stronger launch following pre-chemo approval," he wrote in a recent note to clients.

- read Medivation's release
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